1. Field of the Invention
The present invention relates to a facsimile device, which cannot only carry out ordinary facsimile communication via a public switched telephone network but also implement real-time internet facsimile communication by the ITU-T T.38 recommendation protocol of International Telecommunication Union (ITU) or send image data of facsimile communication as an email attachment file via a gateway device connected to a computer network like the Internet.
2. Description of the Related Art
In recent years, more people use the computer communication network, which can receive and send various data via the more networked Internet by connecting LAN (Local Area Network) to a communication line. In case of using the communication network like this, users can communicate with computers all over the world by only bearing the communications cost (connection fees and communications fee to ISP (Internet Service Providers)) to the nearest ISP.
The send and receive process of image data between facsimile device in case that facsimile communication is carried out by using either protocol, T.38 or SMTP via the gateway device connected to the Internet as a computer communication network will be described below, with reference to FIG. 12.
FIG. 12 shows a transmitting facsimile device 100 and a receiving facsimile device 200. Moreover, 300 shows a transmitting gateway device and 400 shows a receiving gateway device, respectively. The gateway device here means the device having a function to connect a public switched telephone network PSTN to the Internet NTW, and it is installed in the above ISP or the like. Moreover, these gateway devices 300 and 400 have a facsimile communication function by T.30 protocol, a real-time Internet facsimile communication function by T.38 protocol and an email communication function by SMTP.
First, the case of using the communication function by T.38 protocol will be described. The facsimile device 100 modulates the transmitting image data to an analogue audio signal, and sends it to the gateway device 300 via the public switched telephone network PSTN by the conventional facsimile communication protocol (T.30 protocol). Next, the gateway device 300 demodulates the analogue audio signal of the received image data from the facsimile device 100 to the digital signal, and sends it to the gateway device 400 via the Internet NTW by T.38 protocol. Moreover, the gateway device 400 modulates the received digital signal from the gateway device 300 to the analogue audio signal, and sends it to the facsimile device 200 via the public switched telephone network PSTN according to the conventional facsimile communication protocol. Therefore, the facsimile device 200 can receive the received image data from the facsimile device 100 in real time, by demodulating the analogue audio signal transmitted from the gateway device 400 to image data.
Moreover, as mentioned above, the communication between the facsimile device 100 and the gateway device 300 and between the gateway device 400 and the facsimile device 200 is implemented according to the ITU-T T.30 recommendation of International Telecommunication Union (ITU), which prescribes facsimile communication using the public switched telephone network. Moreover, the communication between the gateway device 300 and the gateway device 400 is carried out according to the T.38 recommendation by ITU, which prescribes facsimile communication using the computer communication network.
Next, the case of using the email function by SMTP will be described with reference to the above-mentioned FIG. 6. The facsimile device 100 modulates transmitting image data to an analogue audio signal by the conventional facsimile communication protocol, and sends it to the gateway device 300 via the public switched telephone network PSTN.
The gateway device 300 demodulates the received analogue audio signal from the facsimile device 100 to image data, and converts this to TIFF format (Tagged Image File Format) that is a general image format used in computers. Moreover, the specification of TIFF is open to the public by Adobe System Co., and the corresponding classes are defined in order to deal with various data of not only black and white but also multivalued monochrome and full color and the like. The G3-type image data is defined in the CLASS F, one of those classes. Accordingly, the receiving image data from the facsimile device 100 can be converted to TIFF format by doing the relatively easy process such as to put the TIFF header information of CLASS F to the beginning of the image data. Hereafter, the facsimile image data attached the TIFF header information of CLASS F is called “TIFF image data”.
Next, the gateway device 300 converts a binary data of TIFF image data to text data, as some computers which cannot deal with the email by the binary data are also connected to the Internet. Therefore, in case of sending the binary data like TIFF image data, the data is converted to a text data first and transmitted in order to send email certainly to the destination. By the way, the text data handled in the Internet is prescribed as a 7-bit code in RFC (Request For Comments) 822 that is the document published by IETF (Internet Engineering Task Force).
Consequently, to cite one example, using the base 64, one of the encoding types of MIME (Multipurpose Internet Mail Extensions), the binary data is converted to the text data by being replaced by one of the 64-type characters (uppercase and lowercase alphabet, number, +, /) by a 6-bit unit. By the way, MIME is prescribed in the aforementioned RFC, and encoding types like “7bit”, “8bit” and “binary” are also prescribed as well as the above-mentioned base 64, for example.
Next, the gateway device 300 changes the transmitting file to the email format. To be more precise, the file is edited to the email format by putting TIFF image data converted to text data to the mail header information as the communication management information. The operation by the gateway device 300 like this is essential as the Internet email is prescribed to put the prescribed header information, and in transmitting, the header information, comprising “Date:” (time of origin of the email), “From:” (sender of the email), “To:” (destination of the email), “Subject:” (title of the email, to be more precise, the encoded system) and “Cc:” (destination of the email copy), is added to the beginning of TIFF image data as shown in FIG. 13.
Next, the gateway device 300 sends the email prepared as shown in the above to the gateway device 400 via the Internet NTW by SMTP, and the gateway device 400 separates the body and the communication management information (mail header) from the email received from the gateway device 200 and picks up only TIFF image data converted to text data and converted this to the TIFF format that is a binary data. Moreover, after converting to image data in the ordinary facsimile method, the data is transmitted to the facsimile device 200 by the conventional facsimile communication protocol.
The facsimile communication using the computer communication network (the Internet NTW) between the facsimile device 100 and the facsimile device 200 can be implemented via the gateways 300 and 400 connected by the Internet NTW, having T.38 protocol or SMTP function like this.
However, as mentioned above, in case that facsimile communication is implemented using the Internet NTW even in using either protocol, T.38 or SMTP, the transmitting-side facsimile device 100 does not call for the receiving-side facsimile device 200, but the transmitting-side gateway device 300 is called for via the public switched telephone network PSTN. Accordingly, in this case, the facsimile number (the telephone number) of the receiving-side facsimile device 200 needs to be delivered to the transmitting-side gateway device 300. Accordingly, in case of transmitting an image data from the facsimile device 100 to the facsimile device 200, users must specify both telephone numbers of the gateway device 300 and the facsimile device 200, and the operation becomes confusing.
Moreover, as the communication via the Internet is so called the connectionless type communication, there is not much reliability compared with connection oriented type communication. Accordingly, in case that facsimile communication is implemented via the Internet NTW compared with the case of using only the public switched telephone network, the communication between the gateway devices 300 and 400 is not completed properly and the possibility that the facsimile device 200 cannot receive image data is higher than ordinary facsimile communication using only the public switched telephone network.